Load raising device



April 19.53 E. L. BAUGH ETAL LOAD RAISING DEVICE Filed Oct. 18, 1950 d, ma "a 55W 5 v m M r 2 T .i w a I 2 3 a y I fatentecl Apr. 21 1953 LOAD RAISING DEVICE Everett L. Baugh, Miamisburg, and De Loss D. Wallace, Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application October 18, 1950, Serial No. 190,718

r 1 This invention relates to an improved device for raising or lowering a load.

It is among the objects of the present invention to provide a dual hydraulically actuated load-raising or lowering device consisting of a pair of fluid motors of the cylinder-piston type, so connected with a source of fluid under pressure that compensation for inequality in the fluiddisplacement capacity of the piston rod containing chambers and the rod free chambers of the respective fluid motors, connected to the source of fluid, isnot required.

In a device constructed to accomplish the aforesaid object, fluid under pressure is simultaneously directed into the rod containing chamber of one fluid motor and into the rod free chamber of the second fluid motor. In response to movement of the pistons by this fluid under pressure, fluid in the rod free chamber of the said one motor is discharged and likewise fluid in the rod containing chamber of the second fluid motor is discharged. This results in concurrent operation of the two fluid motors in opposite directions, that is, the piston rod of the said one fluid motor is retracted r drawn into the cylinder, while the piston rod of the second fluid motor is extended or pushed out of the cylinder of said second motor.

Therefore it is another object of the present invention to provide the load lifting and lowering device with motion transmitting levers connecting the respective piston rods of the two fluid motors with parts of the load so that a unidirectional moving force is applied to the load by the motors,,both of which tend concurrently to either raise or lower the load.

This is accomplished by providingthe fulcrum of the one lever at its one end, the load operating link at its other end and'the piston rod of the one motor at a point between the fulcrum .and link while providing the fulcrum of the other lever intermediate its ends to one of which the piston rod of the second motor is connected and the load connecting link to the other end.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the acaccompanying drawing, wherein apreferred embodiment of the present invention is clearly shown. I

In the drawing: 1 The single drawing is a schematic view illustrating the various elementsof the device and their relative connections. 1 Referring to the drawing, the numeral 20 des- 4 Claims. (01. 60-52) 2 ignates any suitable electric motor of the reversible type which is connectible with a source of electric power shown as a storage battery 2|, by

the operation of an suitable two pole switch 22. This electric motor is operatively connected to and drives a fluid pump 23 having two ports 24 and 25. When operating in one direction the port 24 of the pump acts as the fluid discharge port, the port 25 as the fluid intake port. When the pump operates in the opposite direction, port 25 becomes the discharge port and port .24 the intake port.

Two fluid motors 30 and 3| are provided, these fluid motors being of the cylinder-piston type. In the cylinder of motor 30 there is provided a piston 32 having a piston rod 33 attached theret which extends to the outside of the motor through one cylinder head thereof. Fluid motor 3| has a piston 34 within its cylinder, this piston havin rod 35 attached thereto which also extends through one cylinder head to the exterior of the motor 31. Both fluid motors are preferably pivotally supported at their ends opposite the piston rod ends, motor 30 being pivotally supported on the anchor plate 36 and motor 3| on the anchor plate 31. 7

It will be seen that the fluid displacement capacities of the chambers on opposite sides of the pistons in the fluid motors differ per unit of Dis-.- ton movement inasmuch as the one chamber has the piston rod extending therethrough while the chamber on the opposite side of the piston is free of the piston rod. Thus the piston rod contain= ing chamber in each cylinder is of lesser fluid displacement capacity per unit of piston movement than the chamber. on the opposite side of the piston. which does not containv the piston rod.

The present invention has for its object to provide dual fluid motors for raising or lowering a load without the need of compensation due to piston rod displacement in the two fluid motors. To accomplish this, the one port of the fluid pump; for instance port 24, is connected to the rod containing chamber of fluid motor 30 by means of the conduit '40 and is also connected to the rod free chamber of the motor 3! by means of the branch conduit 4|. The other port 25 of the pump is connected to the rod containing chamber of the fluid motor 3| by conduit 42, a branch conduit '43 connecting said port with'the rod free chamber of the fluid motor 30. Thus, when the pump 23 is being operated by the electric motor 20- to cause the port 24 of the pump 23 toact as the fluid discharge port and the port 25.of-.said pump. to'act as the fluid intake port;

then fluid pressure is directed to the rod containing chamber of motor 30 to force the piston 32 in this motor downwardly as regards the drawing, thereby retracting or drawing the piston rod 33 further into the cylinder. At the same time fluid pressure from the pump 23 is directed'lrom'itsiport "through-the branch conduit 4| into the rod free chamber beneath the piston 34 in the motor 3| thereby moving said piston upwardly as regards the drawing and extending or pushing the rod 35 outwardly of the fluid motor 3|. On the contrary, when'the pump 23 operates in the opposite-:direction,.port.25 becomes the discharge port and port 24 the intake port then the piston 34 oi-thefluid motor 31 is forced downwardly as regards the drawing to retract or draw the rod 35 into .thefluid motor and at the same time piston 32 in fluid motor 30 is moved upwardly to push rod 33 out of the fluid motor 30. The intake port of the pump, in this instance, the port 24,,receives fluid from the rod containing chamber of the fluid motor 30 and also from'the rodfree :chamber of the fluid mo- .tor 31. From this it will be seen that operation of the .pump 23 in one direction causes concurrent .operation of the two fluidmotors30 and 3| in opposite directions. The reverse operation of the pump .23 results in "the same manner, that .is, concurrent operation of the fluid motors in opposite directions.

In order to transmit unidirectional .forces to the load actuating mechanism to raise or tollowor said load, translating devices are provided which operatively connect'the .load with the two fluid motors 30 and 3|. These translating devices consist of levers constructed and arranged :toreverse the concurrent opposite operation of 'thetw zflu'idmotors 3|! and 3| into .a'unidirectional force applying movement. .The lever 50 is -Iulcrumed at its extreme one end to the stationary .base The other extreme :end of the lever 50 has a link .52 attached thereto, which link .is suitably connected to the load iEor actuating it. The piston rod 33 of the fluid motor 30 is anchoredto ,lever 50 intermediate the fulcrum 5| and the point of connection of .link 52. On the other hand, link 60, .for .fluid motor 3|, is vfulcrumedto the stationary support 6| intermediate its lends. Link 62 .operatively connected to the .load, is hingedly connected to one .end of link 1611, the other'end .of said linkhaving the pision rod ;35 of motor J3.| attached thereto. Thus, whentherrod :33 :isbeing retracted ordrawn into its fluidmotor 30, .a clockwise movement of lever Ill willobtain to move the link I52 to lower the load. Concurrently, motor 33 is extending or pushing its rod 35 outwardly and thus a clockwise rotation of lever 60 will obtain, causing the 62 to be moved .in thesame direction as link 52 to lower the load. A reversal of fluid motor .operation, that is, when .fluidmotor .30 operates to push its piston rod 33 outwardly or into the extended position, the lever 5|] moves link 52 to raise theload while the concurrent retraction of rod 35 in fluid motor 3| will result in movement of the lever 60 also to movelink .62 'npwardlyior raising the load.

.In order to compensate .ior :any .fluidleakage which might occur in the system or :any reduction of the fluid in the closed circuits of thesystem for any other reason, there is provided a replenishing source of fluid supply. areservoir connected between the conduits l0 and 42 leading from the pump ports. and .25 :respectively. Any suitable check valves are provided in con- 4 nection with reservoir 10, these check valves being operative to permit fluid to flow from the reservoir into the conduit which is in the suction or low pressure operating side of the system if any additional fluid is necessary to replace that lost by leakage or any other cause. More specifica1ly,'iI conduit '40 ison-the suction or the low pressure operating side of the system then, it the fluid supply needs replenishing, fluid will flow :Irom the reservoir 10 into the conduit 40, joining the fluid flow to the intake port 24 of the pump to replenish for any fluid lost. On the contrary, if conduit is on the suction or low pressure side of the circuit during operation and the system needs fluid replenishment, fluid will flow from the reservoir Ill into the conduit 42 to join the fluid flowing to the port 25 of the pump acting as the intake port in this instance.

From the aforegoing it may be seen that applicants have provided a novel circuit arrangement whereby fluid motors of the cylinder 'piston type may be operated without necessitating compensation for differential fluid displacement caused by "the presence of a piston rod in one chamber of the cylinder and the absence of the rod in the chamber on the opposite side of the piston therein.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A fluid filled closed circuit .hydraulic lift mechanism for raising or lowering a load, said mechanism comprising in combination, a reversible fluid circulating pump having two ports; two oppositely acting fluid motors each consisting of a cylinder having a piston therein and a rod secured to the piston and extending through one end of the cylinder; conduits connecting one .pump port with the rod containing end of one cylinder and the rod free end of the second cylinder and other conduits connecting the second .pumpport with the rod free end of said one'cylinder and the rod containing end of the second cylinder, whereby operation of the pump eflects concurrent operation of the two fluid motors in opposite directions; and separate motion transmitting and translating means connecting each piston rod with the load, one means consisting of a lever Iulcrumed at one end and the :piston intermediate its sends, the other a lever Iulcrumed intermediate its ends and the rod secured to one end thereof, said means effecting unidirectional power transmission upon said load by both oppositely moving fluid motors.

.2. In a hydraulic lift mechanism for raising or lowering a load, said mechanism comprising in combination, a reversible electric motor, a fluid pump connected to the motor so as to rotate therewith, said motor having two ports; a pair of double, oppositely acting cylinder and piston fluid motors for raising or lowering said load, each having a piston rod extending from one end of the cylinder so that unequal volumes of fluid are displaced at the two ends of each cylinder; conduits connecting one pump port with the rod containing-end of one cylinder and the rod free end :of the second cylinder; other conduits connecting the rod containing end of the second cylinder and the rod free end of said one cylinder with the other .pump .port; and motion transmitting and translating means connecting each fluid motor with the load, said means consisting of two-levers, oneiulcmmed at its end, the other 5 intermediate its ends whereby said fluid motors are capable concurrently to raise or lower the load in response to actuation of the pump in one or the other direction.

3. A fluid filled closed circuit hydraulic lift mechanism for raising or lowering a load, said mechanism comprising in combination, a reversible fluid circulating pump having two ports; two oppositely acting fluid motors each consisting of a cylinder having a piston therein and a rod secured to the piston and extending through one end of the cylinder whereby the chamber on one side of the piston has a lesser fluid displacement capacity per unit of piston movement than the chamber 0n the opposite side of the piston; conduits connecting the one pump port with the smaller capacity chamber of one fluid motor cylinder and with the larger capacity chamber of the second fluid motor cylinder and the other pump port with the larger capacity chamber of said one cylinder and the smaller capacity chamber of said second cylinder whereby operation of the pump efiects concurrent operation of said two fluid motors one in one direction and the other in the opposite direction; and means interposed between each fluid motor and the load, one means being a link fulcrumed at its one end, the other being a link fulcrumed intermediate its ends for translating the concurrent opposite movements of said fluid motors into a unidirec- O tional movement.

4. A fluid filled closed circuit hydraulic lift mechanism for raising or lowering a load, said mechanism comprising in combination, a reversible fluid circulating pump having two ports; two fluid motors each consisting of a cylinder having a piston therein and a rod secured to the piston and extending through one end of the cylinder whereby the chamber on one side of the piston has a lesser fluid displacement capacity per unit of piston movement than the chamber on the opposite side of the piston; conduits connecting the one pump port with the smaller capacity chamber of one fluid motor cylinder and with the larger capacity chamber of the second fluid motor cylinder and the other pump port with the larger capacity chamber of said one cylinder and the smaller capacity chamber of said second cylinder, whereby operation of the pump effects concurrent operation of said two fluid motors one in one direction and the other in the opposite direction; and motion transmitting levers, each having a respective fluid motor piston rod and a load moving rod connected thereto, one lever being pivoted at its one end, the other between the points of connections with the loadand the one fluid motor.

EVERETT L. BAUGH. DE LOSS D. WALLACE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,812,587 Ellis June 30, 1931 1,969,735 Erling Aug. 14, 1934 2,128,349 Redfern Aug. 30, 1938 2,169,340 Falcon Aug. 15, 1939 2,186,015 Erling Jan. 9, 1940 2,198,543 Lauterbach Apr. 23, 1940 2,322,839 Falcon June 29, 1943 2,331,603 Falcon Oct. 12, 1943 2,509,623 Baade May 30, 1950 

